Hitachi, Ltd.

Hitachi Communication Systems, Inc.

Toshihide Fujio

Masataka Takano

A bus type clock supplying system in a communication system with master-slave synchronization includes communication cards connected with transmission lines within a communication system and a clock bus. Each communication card includes a clock supplying section including a frequency divider for extracting a clock from the transmission lines and a tri-state device outputting the clock to the clock bus; a clock receiving section including a clock selector for selecting one clock from a plurality of the bus-type clock lines, and a frequency multiplier for multiplying the frequency of the selected clock; and a monitoring and controlling section having a function of monitoring interruption of clock input, abnormalities in the frequency multiplier, etc., and a function of controlling the tri-state device and the clock selector.

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Yokohama, Japan

Toshihide Fujio